1. Field of the Invention
The present invention relates to changing the color of skin and other materials using the scattering, emission and absorption properties of nanoparticles. Techniques are disclosed for changing the appearance of skin color and making it whiter by removing the redness, blueness or yellowness appearance using particles of size from nanometer to micrometer.
2. Description of the Prior Art
Color is a property of the light that reaches our eyes. The light is emitted from materials in quantum process. The colors we see depend on the frequency (ν) of the light we see. The transition energy is produced from a quantum process with energy ΔE=hν. Different frequencies of visible light are perceived as different colors; the lowest frequency we detect appears to most people as the color red and the highest as violet. Between them range the infinite number of hues. Red (˜620 nm), green (˜530 nm) and blue (˜440 nm) are called the primary colors. By an additive mixture of the primary colors, we can produce different colors in the spectrum. For example, by adding red, green and blue light together the resulting light appears white; and mixing of yellow with blue light gives white. The mixing of paints is an entirely different process from the mixing of colored lights. Paint is composed of pigments-tiny solid particles in scattering host that produce their characteristic colors by the processes of selective absorption or selective transmission of frequencies. The mixture of absorbing pigments results in a subtraction of colors; the observer sees the light left over after absorption taken place. The magenta, cyan, and yellow are called the subtractive primary colors. The pigments of these three colors can be combined to produce any color in the spectrum in painting or printing. When an additive primary and its opposite subtractive primary combine additively-green with magenta, for example, they produce white. Any two colors that add together to produce white are called complementary colors. As mentioned above, the addition of blue and yellow gives white, yellow is the complementary color of blue. Yellow clothes can be whiten by adding a blue emitting dye.
People of different descent have different skin colors, such as yellow for Asian and oriental people. Various medical conditions can also result in skin coloration such as blueness from cyanosis. People face skin problems as they age, like chronic redness called Rosacea. Our skin pigment changes significantly due to the aging effect of ultraviolet light exposure. This results in the formation of a sallow red color. Even though we may feel healthy, this pigment change often creates an unhealthy look. Skin color problems affect large group of people today. To maintain the youthful and healthy look of their face, men and women use cosmetic material daily. Skin color is primarily determined by the amount of melanin present in the skin. A reduction of the amount of melanin in the skin by cosmetic composition can whiten the skin. [U.S. Pat. No. 5,980,904 issued Nov. 9, 1999 to Jesse C. Leverett et al.] Alternatively, the white pigments or color pigments are compounded as cosmetic bases to form cosmetic product for covering skin discolorations and changing the skin appearance [U.S. Pat. No. 6,669,932 issued Dec. 30, 2003 to Imanaka et al.]. A skin-color adjusting method using material that transmits the complementary color of the skin color can make the hyperchromic portion naturally inconspicuous [U.S. Pat. No. 5,690,916 issued Nov. 25, 1997 to Kimura et al.] The prior arts also use multilayer interference film to shift skin color [U.S. Pat. No. 6,833,959 issued Dec. 21, 2004 to Phillips et al.]. Nanotechnology holds the promise for use in cosmetics. Nanoparticulate titania and zinc oxide are used for absorbing UV light in sunscreens. The colorants have been made with semiconductor particles which exhibit sized-quantized absorption of visible light [U.S. Pat. No. 6,913,830 issued Jul. 5, 2005 to Decker et al.].
This patent teaches the use of quantum processes from scattering, emission and/or absorption of radiation in the visible at key wavelengths to alter the appearance of facial color. Since scattering and emission properties of micro- and nanoparticles can alter the color distribution, method to apply the scattering, emission and/or absorption for skin color changing should be explored. We teach that adding scattering of blue light or emitting of blue light to yellow face results in white appearance of the face, adding blue and green light from scattering or emission to red face results in white appearance face.